If you’ve ever tried to explain a psychedelic trip to someone who has never had one, you’ve probably ended up sounding like an insane person. A new study takes a more helpful route. Instead of debating the meaning of a melting wall, researchers watched what a psychedelic does to brain activity as it happened, in awake mice, across the surface of the cortex.

The team, led by researchers linked to Ruhr University Bochum with collaborators in Hong Kong and Singapore, used optical voltage imaging. In plain English, the mice were engineered so specific neurons glow in step with electrical activity, letting the scientists record waves sweeping across the brain without poking it full of electrodes. The full research was published in Communications Biology.

Then they gave the mice psychedelic-like compounds that activate the serotonin 5-HT2A receptor, a key target in classic psychedelics. The headline result was a slow rhythm in the visual cortex at about 5 cycles per second. After the drugs, these 5-Hz bouts popped up more frequently on their own. When the mice saw a visual stimulus, the response got stronger and lasted longer than it did pre-drug.

Making Mice Hallucinate, For science

Here’s where it gets interesting, and slightly unsettling. The 5-Hz activity didn’t stay parked in the primary visual cortex. It aligned with similar activity in the retrosplenial cortex, a region linked to memory and internal context. The paper reports a delay of about 18 milliseconds between the visual cortex and the retrosplenial cortex, consistent with a signal traveling between areas, with the visual cortex frequently leading.

Ruhr University Bochum spells out what the researchers think is happening. “We have observed in earlier studies that visual processes in the brain are suppressed by this receptor,” said Callum White, the study’s first author. And study leader Dirk Jancke describes the end state as “a bit like partial dreaming,” where recall starts muscling into perception.

That interpretation matches the paper’s own language about stronger top-down control of perception, a mechanism that could support visual hallucinations. The brain still takes in information, but the internal feed gets louder, longer, and more synchronized with what you think you’re seeing.

This was a mouse study, so nobody should read it as a finished map of the human mind. Still, a repeatable brain signature helps in two directions at once. It offers a measurable handle on hallucination-like states linked to conditions like psychosis and Parkinson’s disease, and it gives psychedelic therapy research something concrete to track while clinical trials keep rolling.